BKSS

BKSS, short for "Because Konami Said So", is a reference to the often-conflicting nature of some rulings from Konami; if a ruling is given for a card that conflicts with those of other cards with functionally identical effects, or with what is stated in the card's effect itself, Judges and players have to follow the ruling, despite the conflicts, because Konami dictated that that is how the card should be played. In simpler terms, if a card has a ruling that contradicts those of other, similar cards, or its own effects, you have to follow them:

"Because Konami Said So."

Some well-known BKSS instances (such as a conflict between the rulings of "Demise, King of Armageddon" and "Levia-Dragon - Daedalus" which dictating whether or not they would be destroyed by their own effect if a card effect is Chained to the effect that flips them face-down) were later amended to become more clear and less contradictory, but these are usually well past when the cards were initially released, and are usually done with cards that have rulings that conflict with those of other, similar cards.